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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Matt Schulte <matts@commtech-fastcom.com>,
        Aaron Sierra <asierra@xes-inc.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.14 088/183] tty: serial: exar: Relocate sleep wake-up handling
Date:   Wed, 25 Apr 2018 12:35:08 +0200
Message-Id: <20180425103246.029612025@linuxfoundation.org>
In-Reply-To: <20180425103242.532713678@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Aaron Sierra <asierra@xes-inc.com>


[ Upstream commit c7e1b4059075c9e8eed101d7cc5da43e95eb5e18 ]

Exar sleep wake-up handling has been done on a per-channel basis by
virtue of INT0 being accessible from each channel's address space. I
believe this was initially done out of necessity, but now that Exar
devices have their own driver, we can do things more efficiently by
registering a dedicated INT0 handler at the PCI device level.

I see this change providing the following benefits:

    1. If more than one port is active, eliminates the redundant bus
       cycles for reading INT0 on every interrupt.
    2. This note associated with hooking in the per-channel handler in
       8250_port.c is resolved:
        /* Fixme: probably not the best place for this */

Cc: Matt Schulte <matts@commtech-fastcom.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/8250/8250_exar.c |   34 ++++++++++++++++++++++++++++++----
 drivers/tty/serial/8250/8250_port.c |   26 --------------------------
 2 files changed, 30 insertions(+), 30 deletions(-)

--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -37,6 +37,7 @@
 #define PCI_DEVICE_ID_EXAR_XR17V4358		0x4358
 #define PCI_DEVICE_ID_EXAR_XR17V8358		0x8358
 
+#define UART_EXAR_INT0		0x80
 #define UART_EXAR_8XMODE	0x88	/* 8X sampling rate select */
 
 #define UART_EXAR_FCTR		0x08	/* Feature Control Register */
@@ -124,6 +125,7 @@ struct exar8250_board {
 struct exar8250 {
 	unsigned int		nr;
 	struct exar8250_board	*board;
+	void __iomem		*virt;
 	int			line[0];
 };
 
@@ -134,12 +136,9 @@ static int default_setup(struct exar8250
 	const struct exar8250_board *board = priv->board;
 	unsigned int bar = 0;
 
-	if (!pcim_iomap_table(pcidev)[bar] && !pcim_iomap(pcidev, bar, 0))
-		return -ENOMEM;
-
 	port->port.iotype = UPIO_MEM;
 	port->port.mapbase = pci_resource_start(pcidev, bar) + offset;
-	port->port.membase = pcim_iomap_table(pcidev)[bar] + offset;
+	port->port.membase = priv->virt + offset;
 	port->port.regshift = board->reg_shift;
 
 	return 0;
@@ -423,6 +422,25 @@ static void pci_xr17v35x_exit(struct pci
 	port->port.private_data = NULL;
 }
 
+/*
+ * These Exar UARTs have an extra interrupt indicator that could fire for a
+ * few interrupts that are not presented/cleared through IIR.  One of which is
+ * a wakeup interrupt when coming out of sleep.  These interrupts are only
+ * cleared by reading global INT0 or INT1 registers as interrupts are
+ * associated with channel 0. The INT[3:0] registers _are_ accessible from each
+ * channel's address space, but for the sake of bus efficiency we register a
+ * dedicated handler at the PCI device level to handle them.
+ */
+static irqreturn_t exar_misc_handler(int irq, void *data)
+{
+	struct exar8250 *priv = data;
+
+	/* Clear all PCI interrupts by reading INT0. No effect on IIR */
+	ioread8(priv->virt + UART_EXAR_INT0);
+
+	return IRQ_HANDLED;
+}
+
 static int
 exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 {
@@ -451,6 +469,9 @@ exar_pci_probe(struct pci_dev *pcidev, c
 		return -ENOMEM;
 
 	priv->board = board;
+	priv->virt = pcim_iomap(pcidev, bar, 0);
+	if (!priv->virt)
+		return -ENOMEM;
 
 	pci_set_master(pcidev);
 
@@ -464,6 +485,11 @@ exar_pci_probe(struct pci_dev *pcidev, c
 	uart.port.irq = pci_irq_vector(pcidev, 0);
 	uart.port.dev = &pcidev->dev;
 
+	rc = devm_request_irq(&pcidev->dev, uart.port.irq, exar_misc_handler,
+			 IRQF_SHARED, "exar_uart", priv);
+	if (rc)
+		return rc;
+
 	for (i = 0; i < nr_ports && i < maxnr; i++) {
 		rc = board->setup(priv, pcidev, &uart, i);
 		if (rc) {
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -458,7 +458,6 @@ static void io_serial_out(struct uart_po
 }
 
 static int serial8250_default_handle_irq(struct uart_port *port);
-static int exar_handle_irq(struct uart_port *port);
 
 static void set_io_from_upio(struct uart_port *p)
 {
@@ -1904,26 +1903,6 @@ static int serial8250_default_handle_irq
 }
 
 /*
- * These Exar UARTs have an extra interrupt indicator that could
- * fire for a few unimplemented interrupts.  One of which is a
- * wakeup event when coming out of sleep.  Put this here just
- * to be on the safe side that these interrupts don't go unhandled.
- */
-static int exar_handle_irq(struct uart_port *port)
-{
-	unsigned int iir = serial_port_in(port, UART_IIR);
-	int ret = 0;
-
-	if (((port->type == PORT_XR17V35X) || (port->type == PORT_XR17D15X)) &&
-	    serial_port_in(port, UART_EXAR_INT0) != 0)
-		ret = 1;
-
-	ret |= serial8250_handle_irq(port, iir);
-
-	return ret;
-}
-
-/*
  * Newer 16550 compatible parts such as the SC16C650 & Altera 16550 Soft IP
  * have a programmable TX threshold that triggers the THRE interrupt in
  * the IIR register. In this case, the THRE interrupt indicates the FIFO
@@ -3107,11 +3086,6 @@ static void serial8250_config_port(struc
 	if (port->type == PORT_UNKNOWN)
 		serial8250_release_std_resource(up);
 
-	/* Fixme: probably not the best place for this */
-	if ((port->type == PORT_XR17V35X) ||
-	   (port->type == PORT_XR17D15X))
-		port->handle_irq = exar_handle_irq;
-
 	register_dev_spec_attr_grp(up);
 	up->fcr = uart_config[up->port.type].fcr;
 }